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    Chimney Swift Life History


    Habitat TownsChimney Swifts breed in urban and suburban habitats across the eastern half of the United States and southern Canada. They are most common in areas with a large concentration of chimneys for nest sites and roosts. In rural areas they may still nest in hollow trees, tree cavities, or caves. Chimney Swifts forage mostly over open terrain but also over forests, ponds, and residential areas. During migration they forage in flocks over forests and open areas and roost in chimneys at night. They spend the winter in the upper Amazon basin of Peru, Ecuador, Chile, and Brazil, where they are found in open terrain and on roosts in chimneys, churches, and caves.Back to top


    Food InsectsChimney Swifts eat airborne insects. Feeding on the wing, they capture flies, bugs, bees, wasps, ants, mayflies, stoneflies, beetles, caddisflies, fleas, craneflies, and other insects. They grab large insects with their bills; small ones go right down the throat. Chimney Swifts feed over urban and residential neighborhoods, fields, grasslands, shrublands, orchards, forests, and marshes, usually some distance away from nest sites. They can also pick insects from branch tips and “helicopter” down through the foliage to flush out prey. Normally diurnal foragers, they sometimes hunt for insects at night around streetlights or lit windows. They have been reported taking berries from elderberry bushes.Back to top


    Nest Placement

    Nest BuildingAlthough they originally nested in natural sites such as caves and hollow trees of old-growth forests, Chimney Swifts now nest primarily in chimneys and other artificial sites with vertical surfaces and low light (including air vents, old wells, abandoned cisterns, outhouses, boathouses, garages, silos, barns, lighthouses, and firewood sheds). Both members of a breeding pair may fly toward several potential nest locations, then cling side by side at one particular site, with one member of the pair giving a rhythmic chipping call.

    Nest Description

    The nest is a half-saucer of loosely woven twigs, stuck together and cemented to the chimney wall with the bird’s glue-like saliva. Both parents independently contribute to the nest: they break off small twigs with their feet while flying through branches, then return to the nest site with the twigs in their bills. The completed nest measures 2–3 inches from front to back, 4 inches wide, and 1 inch deep.

    Nesting Facts
    Clutch Size:3-5 eggs
    Number of Broods:1-2 broods
    Egg Length:0.7-0.9 in (1.7-2.2 cm)
    Egg Width:0.5-0.6 in (1.2-1.4 cm)
    Incubation Period:16-21 days
    Nestling Period:14-19 days
    Egg Description:Pure white.
    Condition at Hatching:Helpless and naked.
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    Behavior Aerial ForagerChimney Swifts spend their lives airborne, except when they are roosting or on the nest. They perform aerial courtship displays within 2 weeks of arriving on their North American breeding grounds, forming monogamous pairs for the season. In one of the best known displays, two birds fly close together, calling; first the rear bird and then the leader snaps its wings into a V-shape and the two glide together in a downward curve. Unmated birds roost together in large flocks, sometimes even in a chimney occupied by a nesting pair. Often an unmated helper may assist a breeding pair with rearing the young. After the young fledge, small groups of parents and young from several chimneys join larger staging flocks in bigger chimneys nearby. At the end of summer they gather into large groups to migrate to South America. During migration, as many as 10,000 swifts may circle in a tornado-like flock at dusk and funnel into a roosting chimney to spend the night. The lives of these widespread urban birds are surprisingly unstudied, because of their inaccessible nesting and roosting sites and their aerial lifestyle.Back to top


    Conservation DecliningChimney Swifts have been in a long-term, rangewide decline of about 2.5% per year between 1966 and 2015, resulting in a cumulative decline of 72%, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 7.8 million, with 99% breeding in the U.S., and 1% in Canada. The 2014 State of the Birds Report listed the species as a Common Bird in Steep Decline. It rates a 12 out of 20 on the Continental Concern Score. Chimney Swift are not on the 2016 State of North America's Birds' Watch List. These birds probably became much more numerous with European settlement and the building of millions of chimneys. But traditional brick chimneys are now deteriorating and modern chimneys tend to be unsuitable for nest sites. Adding to the problem, some homeowners now cap their unused chimneys. Chimney cleaning during the nesting season can inadvertently destroy nests and kill swifts. Logging of old-growth forests can reduce the availability of natural nest sites. To prevent further decline, people may need to preserve existing chimneys or create new structures specifically for swift nesting; designs can be downloaded from the North American Chimney Swift Nest Site Research Project. Back to top

    Backyard Tips

    Chimney Swifts may take up residence in your brick chimney if you leave the chimney cap off. It’s a good idea to keep the damper closed during summer and to schedule chimney cleanings either before or after the breeding season. If you don’t have a chimney, you can build a swift nesting tower with plans from the North American Chimney Swift Nest Site Research Project.

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    Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

    North American Bird Conservation Initiative. 2014. The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.

    Partners in Flight. 2017. Avian Conservation Assessment Database. 2017.

    Sauer, J. R., D. K. Niven, J. E. Hines, Jr. Ziolkowski, D. J., K. L. Pardieck, J. E. Fallon and W. A. Link. The North American breeding bird survey, results and analysis 1966-2015 (Version 2.07.2017). USGS Patuxent Wildlife Research Center 2017.

    Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

    Steeves, Tanner K., Shannon B. Kearney-McGee, Margaret A. Rubega, Calvin L. Cink and Charles T. Collins. 2014. Chimney Swift (Chaetura pelagica), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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